Finally! Risk Analysis of Nuclear Power Generation (maybe)

I have long wondered how the nuclear industry measures and manages risk.   I am familiar with risk management systems used by process safety engineers, insurance companies, the airline industry, data/software engineers, etc.  Each one employs some sort of risk matrix and performs qualitative and/or quantitative risk analysis by identifying sets of scenarios, their possible costs in human injuries and lives, the cost of the loss of assets and, often, a probabilistic analysis of a particular failure scenario to occur.   The risk exercises are often lengthy in time and manpower and include step by step consideration of Piping and Instrumentation Diagrams (P&ID).  Such analyses are often the cornerstone of  the regulatory approach. However, the process of risk analysis requires data in order to evaluate the probability of an event occurring.  According to the author of this article the nuclear industry never really started with rigorous risk assessment with small reactors in order to gather dependable data that could be applied to large reactors.

Apparently, far from "over regulating" the nuclear industry, the US NRC may have under regulated.

This article reviews a book written by Thomas Wellock,  and is dedicated to that subject.  Wellock has been the official historian of the U.S. Nuclear Regulaltory Commission for over 10 years.  Here are some excerpts from the article. (The original article should be available for free.)

«“Safe Enough? A History of Nuclear Power and Accident Risk” is a refreshingly candid account of how the government, from the nineteen-forties onward, approached the bottom-line question posed in the book’s title.»

"The government, Wellock notes, thought that it could resolve, or at least skirt, the technology’s biggest safety issues by building reactors in the desert of Washington State, “in the middle of sagebrush and rattlesnakes.” But utility companies, keen to avoid constructing expensive long-distance power lines, later argued for locating nuclear power plants closer to their customers in urban areas."

"Wellock cites internal records showing that, in a draft letter written in the late sixties, the A.E.C.’s principal reactor-safeguards committee warned the agency’s top leadership that, unless new emergency cooling technology could be developed, future nuclear reactors were “suitable only for rural or remote sites.”

"The remote-siting approach not only threatened government ambitions for nuclear power by adding to the costs but was a telltale sign of its inherent dangers; nevertheless, the A.E.C. wanted to let plans for building hundreds of large nuclear plants near urban areas move ahead. Wellock finds that the agency’s commissioners intervened to stop the issuance of the letter."

"And yet, even as plants were beginning to be built in larger numbers, regulators were realizing that they didn’t have the tools they needed to make reliable safety estimates. If you have substantial data, risks can be calculated easily. Insurance companies, which pioneered the statistical techniques of risk analysis, look at how often accidents of specific types occur under various circumstances. But the nuclear-power industry that emerged in the fifties and sixties was building big plants before it had developed a track record of operating smaller ones. It had no statistics about the safety of the large units it was constructing—novel, complex, custom-built machines."

In retrospect, one might ask if it may have been wiser to build something akin to SMRs first, before moving on to the giant reactors.  But that would be "monday morning quarterbacking."

"Stephen Hanauer, a senior federal regulatory official at that time, who held a Ph.D. in physics, summarized this “uncomfortable reality” in numerous internal memos. He duly sent them to other A.E.C. officials, often lawyers and political appointees—not scientists—who then filed them away."

"Although government experts couldn’t nail down the probability of an accident, they could use straightforward arithmetic to predict the damage that might result. The results were presented in a 1957 study by the A.E.C.’s Brookhaven National Laboratory. Eight years later, in 1965, Brookhaven updated its analysis of a worst-case scenario. Nuclear plants had grown in scale, and the implications were devastating: a meltdown could cause forty-five thousand deaths, with radioactive contamination creating a potential “area of disaster the size of the State of Pennsylvania.” When the 1965 update landed at A.E.C. headquarters, Wellock writes, “The commission opted to suppress the results. For the next eight years, the draft update sat like a tumor in remission in A.E.C. filing cabinets, waiting to metastasize.” It was made available only in 1973, after the Chicago attorney Myron Cherry demanded its release."

"Containment buildings did prove helpful during the Three Mile Island disaster, in 1979, and at Fukushima, in 2011, as the physicist Frank von Hippel, of Princeton, has pointed out. The containment facilities at the Japanese plant, while not leak-tight, reduced the release of radioactive materials and provided enough time for more than a hundred thousand people to escape immediate harm from the fallout. On the other hand, more than a decade later, some thirty-five thousand people are unable to return to their homes, many of which have been contaminated with cesium-137, a long-lived radioactive substance that emits intense gamma radiation and raises the risk for cancer. Perhaps most alarmingly, the accident at Fukushima nearly caused a fire in a spent-fuel storage pool that was outside the strongbox. According to recent analyses by von Hippel and others, if that had happened, the release of radioactive material could have multiplied a hundredfold, potentially requiring the relocation of as much as a quarter of the Japanese population, depending on which way the winds were blowing. Such an outcome would have threatened metropolitan Tokyo, a hundred and fifty miles away. "

"What is the actual risk, today, of a potentially catastrophic nuclear-plant accident?"

"Wellock’s book notes that some analysts have put forward rough statistics based on the history of the worldwide nuclear industry: the world’s reactors have now been in operation for more than fourteen thousand “reactor-years,” and to date there have been “five core-damage accidents”—Three Mile Island, Chernobyl, and the three reactors at Fukushima. These numbers, in a back-of-the-envelope sense, suggest that the world should expect one full or partial meltdown every six to seven years. If that estimate is plausible—Wellock presents no challenge to it—then the worldwide nuclear program is slightly overdue for its next big surprise. Another study, published in the Bulletin of the Atomic Scientists in 2016, reached the similar conclusion that the “overall probability” of a meltdown in the next decade was almost seventy per cent."

"By the seventies, Con Ed and others had realized that nuclear power was not, in fact, “too cheap to meter.” Building plants was an engineering nightmare. Companies had to pay for cost overruns and delays caused by the fact that construction was often started without a finished design; work had to be done, torn down, and redone until the débutant builders cobbled the plants together. In fact, the death certificate for the U.S. nuclear industry can be dated precisely to the summer of 1974."

"Decades’ worth of evidence testifies to the difficulty, expense, and danger of turning swords into plowshares. It’s still accruing. European utility companies, faced with reduced Russian natural-gas supplies as a result of the Ukraine war, have looked to electricity from France’s nuclear system—the Continent’s largest—as a potential godsend. And yet the promise of such help has been upended by the recent discovery of stress-corrosion cracking in pipes located in the critical cooling systems of numerous French nuclear units. A dozen reactors have been shut down, and no one knows how long it will take to fix them. It may take years. Meanwhile, the heat wave and drought in Europe this summer have forced other units to go offline, since river water flow no longer suffices as an adequate coolant. Altogether, French nuclear capacity has been effectively cut in half. The fact that nuclear power has fallen on its face when it is needed most is a hint that it is not the key to world energy security."

Finally:

"Henry Kendall, and several books based on extensive reporting for this magazine—have concluded that nuclear power’s potential contribution to clean energy has been compromised by safety shortcuts taken by the industry, and by lax government regulation of day-to-day safety practices at the plants."

From the sixties onward, the A.E.C. used talking points that presented the risks of catastrophic nuclear accidents as “exceedingly low” and “vanishingly small.”

We know how that turned out.